Attractive Dispersion Interactions Versus Steric Repulsion of tert-Butyl groups in the Crystal Packing of a D3h -Symmetric Tris(quinoxalinophenanthrophenazine)

Abstract

The crystalline packing of a π-extended D3h -symmetric triptycene reveals a particular π stacking motif with an almost-eclipsed arrangement of adjacent π planes despite the steric repulsion of tert-butyl substituents. Four model compounds were analyzed by using single-crystal X-ray diffraction and theoretical calculations to study the influence of dispersion interactions of molecular parts and understand the relationship between the molecular structure and this unique packing motif.

Keywords: crystal engineering; density functional calculations; dispersion interactions; heteroacenes; triptycenes.